Attachment for protractors.



0. J..WILLIAMS. ATTACHMENT FOR PROTRAGTORS. APPLICATION FILED MAR.28, 1914.

Patented Mar. 9, 1915.

WITNESSES THE NORRIS PETERS ca. F'HOTO-LITHO.. WASHING mm, D. C,

UNITE STATES PTEN FFIGE.

OWEN J". WILLIAMS, 0F DULUTH, MINNESOTA.

ATTACHMENT FOB PROTRACTORS.

Application filed March 28, 1914.

To all whom it may concern:

Be it known that I, GWEN J. WILLIAMS, a citizen of the United States, residing at Duluth, in the county of St. Louis and State of Minnesota, have invented certain new and useful Improvements in Attachments for Protractors, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to improvements in attachments for protractors, the primary object of which is to construct a device which may be easily and quickly attached to a protractor, of the common form, without necessitating any change or modification therein.

Another object of the present invention is to construct an attachment of such character that when applied to a protractor will result in rendering the protractor easily and conveniently applicable to any straight edge.

I am aware that many forms of improved protractors have been invented, but the present improvement evolves an exceedingly simple attachment for a standard protractor now in general use, and which, when used in conjunction therewith, necessitates no alterations whatever in the protractor or the graduations thereupon.

In the accompanying drawings: Figure 1 is a side elevation of a standard protractor equipped with my device and shown in use against the working edge of a T-square. Fig. 2 is a top plan view of the attachment. Fig. 3 is a cross-sectional view on the line AB of Fig. 1.

Referring now to the drawing in which like letters of reference indicate similar parts in the different figures, my attachment comprises a right angle-shaped piece 2 which is formed of a flat piece of any material, but I have shown it to be constructed of metal as an illustration. This sheet of metal has two opposed arms let formed at right angles to each other. and a center arm 3. The outer edges of the arms 4-4 are provided with inwardly turned lips or flanges 5-5 and the outer edge of the arm 3 is similarly provided with a lip or flange 6.

My attachment 2 may be easily attached to a protractor 1 by slipping the protractor 1 within the lips 55 and 6 so that the lips 55 overlap the outer circumferential edge of the protractor and the lip 6 the inner edge thereof. By this construction, after one Specification of Letters Patent.

Patented Mar. 9, 1915.

Serial No. 827,806.

corner of the protractor has been placed pointing directly toward the apex of the angle, it may be readily slipped around and become mounted on the attachment within the lips 6 and 5-5 as is clearly evident. The outer-most longitudinal dimension of each arm 4: of the attachment is constructed of a length to be exactly equal to the radius of the circle forming the protractor. Thus, the degree of the incline of the chord of the protractor is read at the ends 77 of the arms 4.4:.

In the diagram shown, the chord line 9 of the protraotor is a 45 degree angle to the edge of the T-square 8 upon which the protractor and its attachment is shown being worked. The outer turned edges 5-5 of the angle may be made more extensive and con tinue the entire length of each arm 4:, as is in dicated in dotted lines Fig. 2. This modification in construction is shown and suggested as it might be found to form a more rigid and stronger device.

Having thus described my invention what I claim and desire to secure by Letters Patent is:

1. The combination with a circular protractor, of an attachment therefor. said attachment comprising a body portion having two uninterrupted arms disposed at right angles to each other. of inwardly projecting flanges integral with the said arms, and an opposed flange intermediate the firstmentioned flanges and integral with said body portion, for the purpose described.

2. The combination with a circular pro tractor having a straight edge, of an attachment therefor comprising a body portion having two uninterrupted arms at right angles to each other, and of a length exactly equal to the radius of the protractor, said arms providing means whereby the attachment to the protractor is adiustably made and the angle of the said straight edge with respect to said arms may be determined.

3. The combination with a circular protractor having outer and inner peripheral edges, of an attachment therefor, comprising a right angular sheet, means integral with the said sheet for engaging the outer and inner peripheral edges of the protractor.

4. The combination with a circular protractor having outer and inner peripheral edges, of an attachment therefor comprising a right angular sheet, lips carried on the outer edges, an arm carried by the plate be tween its right angular sides having a lip thereon, said protractor arranged adjacent the plate and having its inner and outer peripheral edges frictionally engaged by the lips on the edges and the arm carried by the plate, the right angular edges of the said plate being of a length equal to the radius of the protractor.

6.The combination with a circular protractor, of an attachment therefor comprising a right angular sheet, lips formed on the 05 m of this patent may be obtained for five cents each, by, addressing the G'onimissioher of outer edges of the said sheet adapted to hold the said protractor, the right angular edges of the sheet being equal to the radius of the protractor, V V

7'. The combination with a circular prot iactor, oi an attachment therefor, comprisiin'g a plate having two sides disposed at right angles to each other, engaging means carried by the outer ends of said sides, the said sides bei g of a length equal to the radius of the said protractor. p 8.- The combination with a circular protracto'r, of an attachment therefor comprising a body-portion having two sides disposed at right angles to each other and means carried by the said body -'portion adapted to engage and hold the said protractor. V p

In testimony whereof I hereunto afiii; my signature in the presence of two witnesses.

OWEN J. WILLIAMS.

Witnesses LALIBERTE, 'S. GEO. STEVENS.

Washington, D. 0.

Patents, 

